Re: [Qemu-devel] [PATCH v8 3/4] qemu-img: Add compare subcommand

[Kevin Wolf]

Am 14.01.2013 11:26, schrieb Miroslav Rezanina:
> This patch adds new qemu-img subcommand that compares content of two disk
> images.
> 
> Signed-off-by: Miroslav Rezanina <address@hidden>
> ---
>  qemu-img-cmds.hx |    6 ++
>  qemu-img.c       |  266 
> ++++++++++++++++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 272 insertions(+), 0 deletions(-)

You also need to add documentation to qemu-img.texi. A description of
the exit codes should probably go there.

> diff --git a/qemu-img-cmds.hx b/qemu-img-cmds.hx
> index 90b93e0..bc1ccfa 100644
> --- a/qemu-img-cmds.hx
> +++ b/qemu-img-cmds.hx
> @@ -27,6 +27,12 @@ STEXI
>  @item commit [-q] [-f @var{fmt}] [-t @var{cache}] @var{filename}
>  ETEXI
>  
> +DEF("compare", img_compare,
> +    "compare [-f fmt] [-F fmt] [-p] [-q] [-s] filename1 filename2")
> +STEXI
> address@hidden compare [-f @var{fmt}] [-F @var{fmt}] [-p] [-q] [-s] 
> @var{filename1} @var{filename2}
> +ETEXI
> +
>  DEF("convert", img_convert,
>      "convert [-c] [-p] [-q] [-f fmt] [-t cache] [-O output_fmt] [-o options] 
> [-s snapshot_name] [-S sparse_size] filename [filename2 [...]] 
> output_filename")
>  STEXI
> diff --git a/qemu-img.c b/qemu-img.c
> index 8d55829..0c12692 100644
> --- a/qemu-img.c
> +++ b/qemu-img.c
> @@ -693,6 +693,272 @@ static int compare_sectors(const uint8_t *buf1, const 
> uint8_t *buf2, int n,
>  
>  #define IO_BUF_SIZE (2 * 1024 * 1024)
>  
> +static int64_t sectors_to_bytes(int64_t sectors)
> +{
> +    return sectors << BDRV_SECTOR_BITS;
> +}
> +
> +static int64_t sectors_to_process(int64_t total, int64_t from)
> +{
> +    int64_t ret = total - from;
> +
> +    if (ret > (IO_BUF_SIZE >> BDRV_SECTOR_BITS)) {
> +        return IO_BUF_SIZE >> BDRV_SECTOR_BITS;
> +    }
> +
> +    return ret;
> +}

return MIN(total - from, IO_BUF_SIZE >> BDRV_SECTOR_BITS) would be a bit
simpler.

> +
> +/*
> + * Check if passed sectors are empty (not allocated or contain only 0 bytes)
> + *
> + * Returns 0 in case sectors are filled with 0, 1 if sectors contain non-zero
> + * data and negative value on error.
> + *
> + * @param bs:  Driver used for accessing file
> + * @param sect_num: Number of first sector to check
> + * @param sect_count: Number of sectors to check
> + * @param filename: Name of disk file we are checking (logging purpose)
> + * @param buffer: Allocated buffer for storing read data
> + * @param quiet: Flag for quiet mode
> + */
> +static int check_empty_sectors(BlockDriverState *bs, int64_t sect_num,
> +                               int sect_count, const char *filename,
> +                               uint8_t *buffer, bool quiet)
> +{
> +    int pnum, ret = 0;
> +    ret = bdrv_read(bs, sect_num, buffer, sect_count);
> +    if (ret < 0) {
> +        error_report("Error while reading offset %" PRId64 " of %s: %s",
> +                     sectors_to_bytes(sect_num), filename, strerror(-ret));
> +        return ret;
> +    }
> +    ret = is_allocated_sectors(buffer, sect_count, &pnum);
> +    if (ret || pnum != sect_count) {
> +        qprintf(quiet, "Content mismatch at offset %" PRId64 "!\n",
> +                sectors_to_bytes(ret ? sect_num : sect_num + pnum));
> +        return 1;
> +    }
> +
> +    return 0;
> +}
> +
> +/*
> + * Compares two images. Exit codes:
> + *
> + * 0 - Images are identical
> + * 1 - Images differ
> + * 2 - Error occurred
> + */
> +static int img_compare(int argc, char **argv)
> +{
> +    const char *fmt1 = NULL, *fmt2 = NULL, *filename1, *filename2;
> +    BlockDriverState *bs1, *bs2;
> +    int64_t total_sectors1, total_sectors2;
> +    uint8_t *buf1 = NULL, *buf2 = NULL;
> +    int pnum1, pnum2;
> +    int allocated1, allocated2;
> +    int ret = 0; /* return value - 0 Ident, 1 Different, 2 Error */
> +    int progress = 0, quiet = 0, strict = 0;

Please use bool instead.

> +    int64_t total_sectors;
> +    int64_t sector_num = 0;
> +    int64_t nb_sectors;
> +    int c, pnum;
> +    uint64_t bs_sectors;
> +    uint64_t progress_base;
> +
> +    for (;;) {
> +        c = getopt(argc, argv, "hpf:F:sq");
> +        if (c == -1) {
> +            break;
> +        }
> +        switch (c) {
> +        case '?':
> +        case 'h':
> +            help();
> +            break;
> +        case 'f':
> +            fmt1 = optarg;
> +            break;
> +        case 'F':
> +            fmt2 = optarg;
> +            break;
> +        case 'p':
> +            progress = 1;
> +            break;
> +        case 'q':
> +            quiet = 1;
> +            break;
> +        case 's':
> +            strict = 1;
> +            break;
> +        }
> +    }
> +
> +    /* Progress is not shown in Quiet mode */
> +    if (quiet) {
> +        progress = 0;
> +    }
> +
> +
> +    if (optind > argc - 2) {
> +        help();
> +    }
> +    filename1 = argv[optind++];
> +    filename2 = argv[optind++];
> +
> +    /* Initialize before goto out */
> +    qemu_progress_init(progress, 2.0);
> +
> +    bs1 = bdrv_new_open(filename1, fmt1, BDRV_O_FLAGS, true, quiet);
> +    if (!bs1) {
> +        error_report("Can't open file %s", filename1);
> +        ret = 2;
> +        goto out3;
> +    }
> +
> +    bs2 = bdrv_new_open(filename2, fmt2, BDRV_O_FLAGS, true, quiet);
> +    if (!bs2) {
> +        error_report("Can't open file %s", filename2);
> +        ret = 2;
> +        goto out2;
> +    }
> +
> +    buf1 = qemu_blockalign(bs1, IO_BUF_SIZE);
> +    buf2 = qemu_blockalign(bs2, IO_BUF_SIZE);
> +    bdrv_get_geometry(bs1, &bs_sectors);
> +    total_sectors1 = bs_sectors;
> +    bdrv_get_geometry(bs2, &bs_sectors);
> +    total_sectors2 = bs_sectors;
> +    total_sectors = MIN(total_sectors1, total_sectors2);
> +    progress_base = MAX(total_sectors1, total_sectors2);
> +
> +    qemu_progress_print(0, 100);
> +
> +    if (strict && total_sectors1 != total_sectors2) {
> +        ret = 1;
> +        qprintf(quiet, "Strict mode: Image size mismatch!\n");
> +        goto out;
> +    }
> +
> +    for (;;) {
> +        nb_sectors = sectors_to_process(total_sectors, sector_num);
> +        if (nb_sectors <= 0) {
> +            break;
> +        }
> +        allocated1 = bdrv_is_allocated_above(bs1, NULL, sector_num, 
> nb_sectors,
> +                                             &pnum1);
> +        allocated2 = bdrv_is_allocated_above(bs2, NULL, sector_num, 
> nb_sectors,
> +                                             &pnum2);

bdrv_is_allocated_above() can return errors, which need to be checked.

> +        nb_sectors = MIN(pnum1, pnum2);
> +
> +        if (allocated1 == allocated2) {
> +            if (allocated1) {
> +                ret = bdrv_read(bs1, sector_num, buf1, nb_sectors);
> +                if (ret < 0) {
> +                    error_report("error while reading offset %" PRId64 " of 
> %s:"
> +                                 " %s", sectors_to_bytes(sector_num), 
> filename1,
> +                                  strerror(-ret));
> +                    ret = 2;
> +                    goto out;
> +                }
> +                ret = bdrv_read(bs2, sector_num, buf2, nb_sectors);
> +                if (ret < 0) {
> +                    error_report("error while reading offset %" PRId64
> +                                 " of %s: %s", sectors_to_bytes(sector_num),
> +                                 filename2, strerror(-ret));
> +                    ret = 2;
> +                    goto out;
> +                }
> +                ret = compare_sectors(buf1, buf2, nb_sectors, &pnum);
> +                if (ret || pnum != nb_sectors) {
> +                    ret = 1;
> +                    qprintf(quiet, "Content mismatch at offset %" PRId64 
> "!\n",
> +                            sectors_to_bytes(
> +                                ret ? sector_num : sector_num + pnum));
> +                    goto out;
> +                }
> +            }
> +        } else {
> +            if (strict) {
> +                ret = 1;
> +                qprintf(quiet, "Strict mode: Offset %" PRId64
> +                        " allocation mismatch!\n",
> +                        sectors_to_bytes(sector_num));
> +                goto out;
> +            }
> +
> +            if (allocated1) {
> +                ret = check_empty_sectors(bs1, sector_num, nb_sectors,
> +                                         filename1, buf1, quiet);
> +            } else {
> +                ret = check_empty_sectors(bs2, sector_num, nb_sectors,
> +                                         filename2, buf1, quiet);
> +            }
> +            if (ret) {
> +                if (ret < 0) {
> +                    ret = 2;
> +                }
> +                goto out;
> +            }
> +        }
> +        sector_num += nb_sectors;
> +        qemu_progress_print(((float) nb_sectors / progress_base)*100, 100);
> +    }
> +
> +    if (total_sectors1 != total_sectors2) {
> +        BlockDriverState *bs_over;
> +        int64_t total_sectors_over;
> +        const char *filename_over;
> +
> +        qprintf(quiet, "Warning: Image size mismatch!\n");
> +        if (total_sectors1 > total_sectors2) {
> +            total_sectors_over = total_sectors1;
> +            bs_over = bs1;
> +            filename_over = filename1;
> +        } else {
> +            total_sectors_over = total_sectors2;
> +            bs_over = bs2;
> +            filename_over = filename2;
> +        }
> +
> +        for (;;) {
> +            nb_sectors = sectors_to_process(total_sectors_over, sector_num);
> +            if (nb_sectors <= 0) {
> +                break;
> +            }
> +            ret = bdrv_is_allocated_above(bs_over, NULL, sector_num,
> +                                          nb_sectors, &pnum);

Error checking again.

> +            nb_sectors = pnum;
> +            if (ret) {
> +                ret = check_empty_sectors(bs_over, sector_num, nb_sectors,
> +                                          filename_over, buf1, quiet);
> +                if (ret) {
> +                    if (ret < 0) {
> +                        ret = 2;
> +                    }
> +                    goto out;
> +                }
> +            }
> +            sector_num += nb_sectors;
> +            qemu_progress_print(((float) nb_sectors / progress_base)*100, 
> 100);
> +        }
> +    }
> +
> +    qprintf(quiet, "Images are identical.\n");
> +    ret = 0;
> +
> +out:
> +    bdrv_delete(bs2);
> +    qemu_vfree(buf1);
> +    qemu_vfree(buf2);
> +out2:
> +    bdrv_delete(bs1);
> +out3:
> +    qemu_progress_end();
> +    return ret;
> +}
> +
>  static int img_convert(int argc, char **argv)
>  {
>      int c, ret = 0, n, n1, bs_n, bs_i, compress, cluster_size, 
> cluster_sectors;
> 

Kevin